SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_is_tls, SSL_is_quic, SSL_version - get the protocol

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       Licensed under the Apache License 2.0 (the "License").  You may not use this file  except  in  compliance
       with  the  License.   You  can  obtain  a  copy  in  the  file  LICENSE  in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.5.0                                              2025-06-04                              SSL_GET_VERSION(3SSL)

       For SSL, TLS and DTLS protocols SSL_client_version() returns the numeric protocol version advertised by
       the client in the legacy_version field of the ClientHello when initiating the connection. Note that, for
       TLS, this value will never indicate a version greater than TLSv1.2 even if TLSv1.3 is subsequently
       negotiated. For QUIC connections it returns OSSL_QUIC1_VERSION.

       SSL_get_version() returns the name of the protocol used for the connection.  SSL_version() returns the
       numeric protocol version used for the connection.  They should only be called after the initial handshake
       has been completed.  Prior to that the results returned from these functions may be unreliable.

       SSL_is_dtls() returns 1 if the connection is using DTLS or 0 if not.

       SSL_is_tls() returns 1 if the connection is using SSL/TLS or 0 if not.

       SSL_is_quic() returns 1 if the connection is using QUIC or 0 if not.

       The  SSL_is_dtls() function was added in OpenSSL 1.1.0. The SSL_is_tls() and SSL_is_quic() functions were
       added in OpenSSL 3.2.

       SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_is_tls, SSL_is_quic, SSL_version - get the protocol
       information of a connection

SSL_get_version() returns one of the following strings:

       SSLv3
           The connection uses the SSLv3 protocol.

       TLSv1
           The connection uses the TLSv1.0 protocol.

       TLSv1.1
           The connection uses the TLSv1.1 protocol.

       TLSv1.2
           The connection uses the TLSv1.2 protocol.

       TLSv1.3
           The connection uses the TLSv1.3 protocol.

       DTLSv0.9
           The connection uses an obsolete pre-standardisation DTLS protocol

       DTLSv1
           The connection uses the DTLSv1 protocol

       DTLSv1.2
           The connection uses the DTLSv1.2 protocol

       QUICv1
           The connection uses the QUICv1 protocol.

       unknown
           This indicates an unknown protocol version.

       SSL_version() and SSL_client_version() return an integer which could include any of the following:

       SSL3_VERSION
           The connection uses the SSLv3 protocol.

       TLS1_VERSION
           The connection uses the TLSv1.0 protocol.

       TLS1_1_VERSION
           The connection uses the TLSv1.1 protocol.

       TLS1_2_VERSION
           The connection uses the TLSv1.2 protocol.

       TLS1_3_VERSION
           The connection uses the TLSv1.3 protocol (never returned for SSL_client_version()).

       DTLS1_BAD_VER
           The connection uses an obsolete pre-standardisation DTLS protocol

       DTLS1_VERSION
           The connection uses the DTLSv1 protocol

       DTLS1_2_VERSION
           The connection uses the DTLSv1.2 protocol

       OSSL_QUIC1_VERSION
           The connection uses the QUICv1 protocol.

ssl(7)

        #include <openssl/ssl.h>

        int SSL_client_version(const SSL *s);

        const char *SSL_get_version(const SSL *ssl);

        int SSL_is_dtls(const SSL *ssl);
        int SSL_is_tls(const SSL *ssl);
        int SSL_is_quic(const SSL *ssl);

        int SSL_version(const SSL *s);